Catalyst and hydroconversion process utilizing the same

ABSTRACT

A catalyst is provided which comprises a hydrogenation component and a support comprising agglomerates of alumina having initially not more than 0.20 cubic centimeters per gram of its pore volume in pores greater than about 400 Angstroms in diameter and a minor amount of silica. A process for the hydroconversion of hydrocarbonaceous oils utilizing the catalyst is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 066,572 filed Aug. 15, 1979 and now abandoned, the teachings ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a catalyst and a process for thehydroconversion of hydrocarbonaceous oils.

2. Description of the Prior Art

Hydroconversion catalysts comprising a hydrogenation component and asupport comprising alumina are well known in the art. Hydroconversionprocesses in which a hydrocarbonaceous oil feed is converted in thepresence of hydrogen and a catalyst comprising a hydrogenation componentand a support comprising alumina are known.

The term "hydroconversion" is used herein to denote a process conductedin the presence of hydrogen in which at least a portion of the heavyconstituents of the hydrocarbonaceous oil chargestock is converted tolower boiling hydrocarbon products while, simultaneously reducing theconcentration of nitrogenous compounds, sulfur compounds and metalliccontaminants.

A method of preparing agglomerates of alumina is disclosed in Akzona'sU.S. Pat. No. 4,159,969, based on Dutch patent application No. 7700810published July 31, 1978, the teachings of which are hereby incorporatedby reference. The Akzona patent also discloses that the agglomerates ofalumina may be composited with catalytically active materials inconventional ways. It has now been found that a catalyst comprising suchagglomerates of alumina having a specified macroporosity will provideadvantages that will become apparent in the ensuing description.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided, a catalystcomprising:

(a) a support having initially a surface area ranging from about 350 toabout 500 m² /g, a total pore volume of about 1.0 to about 2.5 cc/g, notmore than about 0.2 cc/g of said pore volume being in pores having adiameter of more than about 400 Angstroms, said support comprisingagglomerates of alumina and silica, said silica comprising less thanabout 10 weight percent of said support, said agglomerates having beenprepared in an agglomeration zone, under agglomeration conditions,including maintaining the heat introduced into said agglomeration zonein the range of about 10,000 to about 25,000 British thermal units perhour per pound of said alumina, and

(b) a hydrogenation component selected from the group consisting ofelemental metal, metal oxide, metal sulfide of a Group VIB metal and anelemental metal, metal oxide and metal sulfide of a Group VIII metal andmixtures thereof of the Periodic Table of Elements.

In accordance with the invention, there is also provided ahydroconversion process utilizing the above-stated catalyst.

DETAILED DESCRIPTION OF THE INVENTION The Support

A catalyst support comprises agglomerates of alumina and a minor amountof silica. Optionally, minor amounts of other refractory oxides may beincluded in the support. Agglomerates of alumina, also referred toherein as "beaded" alumina, have initially prior to being compositedwith the hydrogenation component, a BET surface area ranging from about350 to about 500 m² /g, a BET total pore volume of about 1.0 to about2.5 cc/g. The agglomerates of alumina initially used as component of thecatalyst must have not more than about 0.20 cc/g of its pore volume inpores having diameter greater than 400 Angstroms (these pores willhereinafter be called macropores). Suitable range of pores havingdiameter greater than 400 Angstroms include from about 0.05 to 0.20cc/g. The agglomerates of alumina may be prepared by a modification ofthe method disclosed in U.S. Pat. No. 4,159,969. According to theteachings of said U.S. patent, alumina agglomerates are prepared bycontacting a hydrous aluminum oxide gel with an organic liquid which isessentially immiscible with water at a given ratio of organic liquid towater, as contained in the gel, such that only a portion of the water isremoved from the hydrous aluminum oxide gel, prior to drying the gel.After the contacting step, according to the teachings of said U.S.patent, any prior art technique for agglomeration can be used. Forexample, the gel which has been contacted with the organic liquid may beplaced in a rotary film evaporator and the liquid phase evaporated offwith continuous agitation. After subjecting the gel to agglomerationconditions and calcination, the alumina agglomerates made in accordancewith the teachings of U.S. Pat. No. 4,159,969 will have a surface arearanging from about 350 to about 500 m² /g (BET) and a pore volumeranging from about 1.0 to about 2.5 cc/g (BET). The alumina agglomeratesutilized as component of the catalyst of the present invention must havea low macroporous volume, that is, the MERPOR pore volume in poresgreater than 400 Angstroms in diameter must be not more than about 0.2cc/g and may range from about 0.05 to 0.2 cc/g. The term "MERPOR" isused herein to designate a mercury penetration method using porosimetermodel 915-2 manufactured by Micrometritics Corporation, Norcross, Ga.The surface tension of the mercury is taken at a contact angle of 140degrees. A pressure of 50,000 psig is used unless otherwise specified.The term "BET" is used herein to designate a nitrogen adsorption methodof Brunauer, Emmett and Teller as shown in the Journal of AmericanChemical Society, vol. 16 (1938) pages 309 to 319. It has been found, inaccordance with the present invention, that the macroporosity of thesealumina agglomerates can be controlled by controlling the rate of heatinput into the agglomeration zone during the vaporization of the liquidphase (that is, the alcohol-water azeotrope) from the gel during theformation of the agglomerates to obtain the desired macroporosity. Whencatalytic metals are included during the formation of the agglomerates,that is, prior to calcination, the calcined catalyst should have amacroporosity of not more than about 0.2 cc/g. In the embodiment inwhich a calcined agglomerate support is subsequently impregnated withthe catalytic metals, the calcined support as well as the finishedcatalyst should have a macroporosity of not more than about 0.2 cc/g(MERPOR). One method of obtaining a macroporosity of less than about 0.2cc/g in accordance with the present invention, is to control the heatintroduced into the agglomeration zone during the vaporization of theazeotrope from the gel during the agglomeration of the alumina supportto a range of about 10,000 to about 25,000 BTU per hour per pound ofalumina. When the catalytic metal components are not present during theformation of the agglomerates, a preferred range is from about 10,000 to20,000 BTU per hour per pound of alumina, more preferably from about13,000 to 15,000 BTU per hour per pound of alumina. When catalytic metalcomponents are included during the formation of the agglomerates priorto calcination, a preferred range of heat input for the vaporization ofthe liquid phase (azeotrope) from the gel is from about 20,000 to about25,000 BTU per hour per pound of alumina.

The catalyst support of the present invention additionally comprises aminor amount of silica, that is, less than about 10 weight percent,based on the weight of the support, preferably from about 1 to about 6weight ercent silica, more preferably from about 1 to about 4 weightpercent silica, based on the support. As disclosed in U.S. Pat. No.4,159,969, sodium silicate may be added to the alumina hydrogel prior togelation to yield silica in the final catalyst. Furthermore, minoramounts of boron oxide, phosphorous pentoxide, titanium oxide, zirconiumoxide, etc. may also be present in the alumina agglomerate-containingsupport.

The Hydrogenation Component

Suitable hydrogenation component include elemental metal, metal oxide,and metal sulfide of the Group VIB metal, and elemental metal, metaloxide and metal sulfide of the Group VIII metal and mixtures thereof ofthe Periodic Table of Elements. The Periodic Table referred to herein isin accordance with Handbook of Chemistry and Physics published byChemical Rubber Company, Cleveland, Ohio, 45th Edition, 1964. Thepreferred Group VIB metal component in the final catalyst is selectedfrom the group consisting of molybdenum oxide, molybdenum sulfide,tungsten oxide, tungsten sulfide and mixtures thereof. The preferredGroup VIII metal component is selected from the group consisting ofnickel oxide, nickel sulfide, cobalt sulfide, cobalt oxide and mixturesthereof. The Group VIII metal component is suitably present in the finalcatalyst in amounts ranging from about 1 to about 6 weight percent,calculated as the oxide, based on the total catalyst. The Group VIBmetal component is suitably present in the final catalyst in amountsranging from about 5 to about 25 weight percent, preferably from about12 to about 18 weight percent, calculated as the oxide, based on thetotal catalyst.

The hydrogenation components may be composited with the support in anysuitable manner and at any stage of the preparation of the catalyst. Forexample, salts of the desired metals may be used to impregnate theagglomerates. The impregnation may be performed before, during or afterformation of the agglomerates, prior to calcination. Alternatively, theimpregnation can be performed after calcination of the agglomerates.

The finished catalyst, after calcination, will have a BET surface arearanging from about 250 to about 450 m² /g; a BET pore volume rangingfrom about 0.9 to about 2.0 cc/g and a macroporosity (pores havingdiameter greater than 400 Angstroms) of about 0.05 to about 0.2 cc/g; asmeasured by MERPOR.

The catalyst may be sulfided prior or during use in a conventional wayas is well known in the art.

The catalyst of the invention is suitable for hydrocarbonhydroprocessing such as hydrodesulfurization, hydroconversion,hydrodenitrogenation, etc. It is particularly suited for hydroconversionof heavy hydrocarbonaceous oils.

Hydroconversion Conditions

Suitable hydroconversion conditions, when utilizing the catalyst of thepresent invention, include a temperature ranging from about 600° toabout 950° F., a pressure ranging from about 500 to about 5000 psig.Preferred hydroconversion conditions include a temperature ranging fromabout 700° F. to about 900° F., more preferably from about 750° F. toabout 850° F., a pressure ranging from about 1000 to 4000 psig, morepreferably from about 2000 to about 3000 psig and a hydrogen rate of1000 to 10,000 standard cubic feet of hydrogen per barrel of oil feed,preferably 4000 to 6000 standard cubic feet of hydrogen per barrel ofoil feed.

The process may be carried out in a fixed bed, moving bed, ebullatingbed, slurry, disperse phase or fluidized bed operation. Preferably, theprocess is carried out in an ebullating bed. Suitable oil feed spacevelocity for ebullating bed operation include 0.1 to 5 V/Hr/V,preferably 0.3 to 1.0 V/Hr/V.

Heavy Hydrocarbonaceous Chargestock

Suitable chargestocks include heavy hydrocarbonaceous oils boiling aboveabout 650° F. at atmospheric pressure, such as for example, petroleumcrude oils, including heavy crude oils; heavy hydrocarbon distillatesboiling in the range of about 650° to 1050° F. at atmospheric pressure,such as gas oils; residual petroleum oils, such as atmosphericdistillation bottoms and vacuum distillation bottoms; bitumens; tar;tarsand oil; shale oil; liquids derived from coal liquefactionprocesses, including coal liquefaction bottoms.

The process is particularly well suited for treating residual oils suchas atmospheric residuum and vacuum residuum.

PREFERRED EMBODIMENTS

The following examples are presented to illustrate the invention.

EXAMPLE 1

Comparative tests were made utilizing a catalyst of the presentinvention, herein designated "Catalyst A" and three prior art catalystsdesignated Catalysts "B", "C" and "D".

Catalyst A was prepared by producing an agglomerated (beaded) aluminasupport comprising about 2 weight percent silica. The support had thefollowing physical properties:

    ______________________________________                                        BET surface area    = 434 m.sup.2 /g                                          BET pore volume     = 1.61 cc/g                                               Average pore diameter                                                                             = 148 Angstroms                                           Pore Volume of 400A+                                                                              = 0.12 cc/g                                               ______________________________________                                    

The above-stated support was impregnated with cobalt and molybdenum toyield 3.3 weight percent CoO and 12.4 weight percent MoO₃ in thecatalyst. No substantial change in the physical properties occurred fromthe impregnation. This catalyst is herein designated "Catalyst A".

The compositions of Catalysts A, B, C and D are given in Table I.

                  TABLE I                                                         ______________________________________                                        Catalyst     A        B        C      D                                       ______________________________________                                        MoO.sub.3, wt. %                                                                           12.4     14.9     15.0   14.9                                    CoO, wt. %   3.3      4.5      3.5    3.1                                     Alumina, wt. %                                                                             82.8     79.8     81.5   82.0                                    Silica, wt. %                                                                              0.9      --       --     --                                      P.sub.2 O.sub.5, wt. %                                                                     0.6      0.8      --     --                                      ______________________________________                                    

These catalysts were tested utilizing a light Arabian vacuum residuumfeed having 3.6 weight percent sulfur, 60 wppm vanadium, 89 weightpercent 1050° F.+ and 0.3 weight percent nitrogen. The conditions usedfor the comparative tests were a temperature of 780° F., a hydrogen rateof 6000 standard cubic feet of hydrogen per barrel of feed, a pressureof 2400 psig, a space velocity of 0.5 volume of feed per volume ofcatalyst per hour in an upflow reactor in which the catalyst wasdisposed in a fixed bed.

The results of these tests are summarized in Table II.

                  TABLE II                                                        ______________________________________                                        Conv. @ 780° F.                                                                    A       B        C       D                                        ______________________________________                                        1050° F. + , wt. %                                                                 67-51   51-36    53-39   59-39                                    Sulfur, wt. %                                                                             96-92   91-80    93-80   95-76                                    Nitrogen, wt. %                                                                           70-64   49-29    41-25   46-25                                    Vanadium, wt. %                                                                           91-83   100-99   100-99  100-99                                   ______________________________________                                    

In each experiment, the range given for the data is for start-of-run andend-of-run with the run length averaging about 21 to 25 days. As can beseen from the data of Table II, Catalyst A was superior to the standardprior art commercial Catalysts B, C and D for all reactions except forvanadium removal.

EXAMPLE 2

To determine the effect of macroporosity on catalyst activity, twocatalysts (Catalysts E and F) prepared using the agglomerate formationmethod were tested. Catalyst E had a macroporosity of about 0.92 cc/g.The catalytic metals were included during the agglomeration step inmaking Catalyst E. Catalyst F, which is a catalyst having themacroporosity in accordance with the present invention, was made byfirst forming the agglomerate (beaded) support followed by impregnationof the calcined support with the catalytic metal components. Thecomposition of both catalysts was 6 weight percent CoO; 20 weightpercent MoO₃ ; 1 weight percent P₂ O₅ ; 73 weight percent Al₂ O₃. Thephysical properties of these catalysts are summarized in Table III.

                  TABLE III                                                       ______________________________________                                                           Catalyst E                                                                            Catalyst F                                         ______________________________________                                        BET surface area, m.sup.2 /g                                                                       445       319                                            BET pore volume, cc/g                                                                              2.19      1.38                                           MERPOR 400A+ pore volume, cc/g                                                                     0.92      0.18                                           Bulk density, g/cc   0.258     0.470                                          ______________________________________                                    

Catalysts E and F were tested in a catalyst screening unit consisting offour reactors in a common sandbath. In each case, 10 cc of each catalystwere charged to a reactor and the catalyst was sulfided for 16 hourswith 10 vol. % H₂ S in H₂ at 750° F. The catalysts were tested at 750°F., 1 V/Hr/V (10 cc/hr), 2250 psig and 6000 SCF/H₂ for about 3 weeks.The feed used in the test was a Cold Lake crude having 4.3 weightpercent sulfur, 165 wppm vanadium and 46 weight percent 1050° F.+material. After approximately 160 hours on oil, the data shown in TableIV were obtained.

                  TABLE IV                                                        ______________________________________                                        Conversion at 750° F.                                                                   Catalyst E  Catalyst F                                       ______________________________________                                        Sulfur, wt. %    78          89                                               Vanadium, wt. %  63          78                                               1050° F.+, wt. %                                                                        32          46                                               ______________________________________                                    

As can be seen from the data of Table IV, Catalyst F, which is acatalyst having the required low macroporosity in accordance with thepresent invention, was superior to Catalyst E which was a catalysthaving a greater macroporosity and which is, therefore, not a catalystof the present invention.

EXAMPLE 3

This example shows that control of the macroporosity of the catalystsupport is obtained by controlling the heat input rate into theagglomerate formation zone and, therefore, the rate of vaporization ofthe alcohol-water azeotrope from the gel during the agglomeration of thealumina support.

To 300 grams of an aluminum oxide gel filter cake having a solidscontent of 4 weight percent, isoamyl alcohol was added in an amountsufficient to provide a weight ratio of alcohol to water, as containedin the gel, of about 0.88. The mixture was placed in a 1 liter flaskwhich was partially immersed in an oil bath. The flask was attached to arotary film evaporator. The pressure was 25 cm Hg. The temperature wasfirst maintained at 90° C. for 1.5 hours by the oil bath. Thetemperature was then increased to 100° C.+ to remove the remainder ofthe alcohol-water azeotrope. The resulting alumina agglomerates weredried and then calcined at about 538° C. for 4 hours. The resultingcatalyst support, is herein designated "support G". The procedure usedto prepare "support G" was similar to the procedure disclosed in U.S.Pat. No. 4,159,969, see particularly Example 2.

The procedure used to prepare "support G" was modified as follows toprepare other supports: a three-liter flask was utilized instead of aone-liter flask and the reactants were tripled. These changes inherentlyreduced the heat input rate into the flask and consequently reduced thevaporization rate. The bath temperature was varied to change the heatinput rate to produce different supports. The results are summarized inTable V.

                  TABLE V                                                         ______________________________________                                        Catalyst Support                                                                            G        H        I      J                                      ______________________________________                                        Flask size    1 liter  3 liters                                               Bath temperature, °C.                                                                90       90       80     100                                    Heat input,                                                                   BTU/hr per 1 lb Al.sub.2 O.sub.3                                                            28678    13746    7963   19434                                  SA, m.sup.2 /gm                                                                             456      401      368    403                                    PV, cc/gm     2.49     1.50     1.25   1.78                                   PD, A         218      150      136    177                                    400A + PV, cc/gm                                                                            0.81     0.08     0.04   0.20                                   ______________________________________                                         SA = surface area                                                             PD = pore diameter                                                            PV = pore volume                                                         

The data of Table V show that control of the macroporosity is directlyrelated to the rate of heat supplied to the vessel or zone of formationof the agglomerates. Catalyst supports H, I and J are suitable supportsfor the catalyst of the present invention since they have not more thanabout 0.2 cc/g of their pore volume in pores having a diameter of morethan about 400 Angstroms.

What is claimed is:
 1. A catalyst comprising:(a) a support havinginitially a surface area ranging from about 350 to about 500 m² /g, atotal pore volume of about 1.0 to about 2.5 cc/g, not more than about0.2 cc/g of said pore volume being in pores having a diameter of morethan about 400 Angstroms, said support comprising agglomerates ofalumina and silica, said silica comprising less than about 10 weightpercent of said support, said agglomerates having been prepared in anagglomeration zone, under agglomeration conditions, includingmaintaining the heat introduced into said agglomeration zone in therange of about 10,000 to about 25,000 British thermal units per hour perpound of said alumina, and (b) a hydrogenation component selected fromthe group consisting of elemental metal, metal oxide, metal sulfide of aGroup VIB metal and an elemental metal, metal oxide and metal sulfide ofa Group VII metal and mixtures thereof of the Periodic Table ofElements.
 2. The catalyst of claim 1, wherein said heat introduced intosaid agglomeration zone ranges from about 10,000 to about 20,000 Britishthermal units per hour per pound of said alumina.
 3. The catalyst ofclaim 1 wherein said hydrogenation component is present in saidagglomeration zone during the preparation of said agglomerates andwherein said heat introduced into said agglomeration zone ranges fromabout 20,000 to about 25,000 British thermal units per hour per pound ofsaid alumina.
 4. The catalyst of claim 1 wherein said pores havingdiameters above about 400 Angstroms comprise from about 0.05 to about0.20 cc/g of the pore volume of said catalyst.
 5. The catalyst of claim1 wherein said silica comprises from about 1 to about 6 weight percentof said support.
 6. The catalyst of claim 1 wherein said silicacomprises from about 1 to about 4 weight percent of said support.
 7. Thecatalyst of claim 1 wherein said catalyst comprises from about 1 toabout 6 weight percent of at least one of said Group VIII metals andfrom about 5 to about 25 weight percent of said Group VIB metals,calculated as the oxides thereof, based on the total catalyst.
 8. Thecatalyst of claim 1 wherein said hydrogenation component is selectedfrom the group consisting of nickel, nickel oxide, nickel sulfide,molybdenum, molybdenum oxide, molybdenum sulfide, tungsten, tungstenoxide, tungsten sulfide, cobalt, cobalt oxide, cobalt sulfide, andmixtures thereof.
 9. The catalyst of claim 1 wherein said catalyst has asurface area ranging from about 250 to about 450 m² /g, a pore volumeranging from about 0.9 to about 2.0 cc/g and not more than about 0.2cc/g of said pore volume being in pores having a diameter of more thanabout 400 Angstroms.